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TECHNICAL LIBRARY

Q: I run DRC, find one-two violations, correct them, then
I re-run DRC to check whether my corrections worked. However re-running
on the whole design is time-consuming. How can I run DRC over a piece
of the layout, in the vicinity of the introduced changes?

A: Recent release of Expert
contain two important features that avoid multiple batch DRC reruns
for the whole design.

"DRC in Area" command allows you to
run DRC script to be run it the selected rectangular area of the
layout.

"DRC Guard" allows monitoring of design
rule violations on the fly while editing the design.

Please read the release notes for Expert v.
156 for details. (All release notes are accumulated in the file
relnotes.txt).

Q1: When I plot my design on a laser
printer some
regions are not plotted at all.

Q2. Stipple patterns on screen
and on plot
look differently.

A: In both cases the reasons
are the same. Unfortunately, color capabilities of screen and plotting
devices often do not match. In particular, some nonsaturated colors
clearly visible on the screen are mapped into white color on the
plot.

One more problem arises if you try to plot a layout
drawn in stipple mode of filling. When preparing data for plotting
the software tries to match RGB values of colors from layout to
the available set of plotter colors. To do so, plotters use dot
patterns of primary colors. These dot patterns may be either regular
or diffuse ones. Stipple mode of filling also uses bit patterns
for filling. When plotter's color dot patterns and stipple patterns
interact, the results can be totally unpredictable. Therefore color
matching has chance to work correctly for solid-filled and wireframe
shapes only.

Expert provides two means to alleviate these
problems:

- plotting style setup, see Figure 1;

- color libraries.

Plotting style setup, among other possibilities,
allows you to assign filling modes and colors for layers different
from the ones used on screen. In particular, in troublesome situations
is is possible to replace stipple filling by hatching. Hatching
is filling by "wireframe" lines rather than by dot patterns,
therefore it does not interfere with color matching tricks. However
this advantage is linked with a drawback: there are six possible
types of hatching, see Figure 1.

Figure 1. Style Setup.

Color libraries allow you to define "named"
colors. This allows you to predefine a set of "good" colors
for further use in setups, see Figure 2.

Moreover, color libraries for plotter and for screen
may contain colors with the same name, but with different numeric
RGB values, so that the named color on screen will look exactly
the same as the color with the same name for printer/plotter. Such
separate color definitions may be prepared for all types of plotters
you have.

Of course, such kind of color/style setup requires
some tedious tuning, including trial printouts. But please remember,
color library tuning must be performed only once.

Figure 2. Color Setup.

Q:Expert's tool bars occupy
too much screen space.
I would like to have more space for layout.

A. In Expert the whole screen
may be used for editing in the following way:

using menu Setup>>Customize assign shortcuts
to most frequently used commands and/or add them into the custom
menu (the one appearing if you depress right mouse button inside
design area).